Collective oscillations of free electrons generate plasmons on the surface of a material. A whispering-gallery microcavity effectively confines the light field on its surface based on the total reflection from its int...Collective oscillations of free electrons generate plasmons on the surface of a material. A whispering-gallery microcavity effectively confines the light field on its surface based on the total reflection from its internal wall. When these two kinds of electromagnetic waves meet each other, the stimulated emissions from an individual ZnO microrod were enhanced more than 50-fold and the threshold was reduced after the whispering-gallery microcavity was coated with a monolayer of graphene and A1 nanoparticles. The improvement of the lasing performance was attributed to the synergistic energy coupling of the graphene/A1 surface plasmons with ZnO excitons. The lasing characteristics and the coupling mechanism were investigated systematically.展开更多
It is essential to develop a single mode operation and improve the performance of lasing in order to ensure practical applicability of microlasers and nanolasers. In this paper, two hexagonal microteeth with varied na...It is essential to develop a single mode operation and improve the performance of lasing in order to ensure practical applicability of microlasers and nanolasers. In this paper, two hexagonal microteeth with varied nanoscaled air-gaps of a ZnO microcomb are used to construct coupled whispering-gallery cavities. This is done to achieve a stable single mode lasing based on Vernier effect without requiring any complicated or sophisticated manipulation to achieve positioning with nanoscale precision. Optical gain and the corresponding ultraviolet lasing performance were improved greatly through coupling with localized surface plasmons of Pt nanoparticles. The ZnO/Pt hybrid microcavities achieved a seven-fold enhancement of intensity of single mode lasing with higher side- mode suppression ratio and lower threshold. The mechanism that led to this enhancement has been described in detail.展开更多
Ag2S/Ag2WO4 composite microrods,with lengths of 0.2-1μm and diameters of 20-30 nm,were fabricated by a facile sonochemical route.The as-synthesized products were intensively investigated by a series of physicochemica...Ag2S/Ag2WO4 composite microrods,with lengths of 0.2-1μm and diameters of 20-30 nm,were fabricated by a facile sonochemical route.The as-synthesized products were intensively investigated by a series of physicochemical characterizations,such as N2 physical adsorption,X-ray diffraction,scanning electron microscopy,transmission electron microscopy,Fourier transform infrared spectroscopy,diffuser reflectance spectroscopy,X-ray photoelectron spectroscopy,photoluminescence spectroscopy and photocurrent response measurements.Ultrasonic irradiation yields an obvious improvement in the photocatalyst texture,for example,an increase in crystallinity and surface area.Moreover,sonochemically fabricated Ag2S/Ag2WO4 microrods display strong visible light absorption and a high transient photocurrent response.The produced intimate Ag2S/Ag2WO4interface between Ag2S and Ag2WO4 crystal phases largely promotes the separation of photogenerated holes and electrons.High photocatalytic activity and stability were obtained over Ag2S/Ag2WO4composite microrods.The dye degradation rate constant of Ag2S/Ag2WO4 was 4.7 times and 29.8times higher than that of bare Ag2WO4 and Ag2S,respectively.展开更多
Developing metal-organic framework(MOF)-based materials with good cyclic stability is the key to their practical application. Fluorinated organic compounds are usually highly chemically stability due to the high elect...Developing metal-organic framework(MOF)-based materials with good cyclic stability is the key to their practical application. Fluorinated organic compounds are usually highly chemically stability due to the high electronegativity of fluorine. Also, the pillared-layer structures based on coordination bonds have better structure and thermal stability than those based on hydrogen bonds. Herein, the fluorinated pillared-layer [Ni(2,3,4,5-tetrafluorobenzoic acid)(4,4-bipyridine)]nMOF([Ni(TFBA)(Bpy)]n) materials were constructed through a facile room-temperature solution reaction and used as electrode materials for supercapacitors. Surprisingly, the size/morphology of Ni(TFBA)(Bpy)nMOFs could be adjusted by varying the synthesis time. Benefting from the short ion diffusion length, unique pillar-layer structure, and strong intercomponent synergy of organic ligands, the Ni(TFBA)(Bpy)nMOF microrods showed a higher electrochemical energy storage capability than bulk MOFs. At the same time, compared to the non-fluorinated [Ni(benzoic acid)(Bpy)]nMOFs(31.5% capacitance decay), the fluorinated Ni(TFBA)(Bpy)n MOFs have a higher cycle stability with only 2.6% capacitance loss after 5000 cycles at 3 m A/cm^(2).展开更多
The morphology of MAX phase powders significantly influences their microwave absorption properties.However,the traditional synthesis via solid-state reactions produces irregular powders,and the preparation of MAX phas...The morphology of MAX phase powders significantly influences their microwave absorption properties.However,the traditional synthesis via solid-state reactions produces irregular powders,and the preparation of MAX phase powders with specific morphology remains a challenge.Herein,(VTiCr)Al C MAX phase microrods were fabricated for the first time in NaCl/KCl molten salts using vanadium,titanium,chromium,aluminum,and short carbon fibers as precursors.It was found that despite acting as a carbon source,carbon fibers also acted as sacrificial templates.By adjusting the molar ratio of metal powders and short carbon fibers,a series of carbon fiber@(V_(0.8)Ti_(0.1)Cr_(0.1))_(2)AlC microrods with core-sheath structure were also obtained.Carbon fiber@(V_(0.8)Ti_(0.1)Cr_(0.1))_(2)AlC microrods with a molar ratio of 8:2 showed the optimum microwave absorption performance.The reflection loss(RL)value reached up to–63.26 d B at 2.40 mm,and the effective absorption bandwidth(EAB)was about 5.28 GHz with a thickness of2.02 mm.Based on the electromagnetic parameter analysis and theoretical simulation,the enhanced microwave absorption performance was attributed to the synergistic effect of different factors like dielectric loss,magnetic loss,multiple reflection,and scattering.This work offers a facile route to modulate the morphology of MAX phase powders and may accelerate its application as microwave absorbers.展开更多
ZnO microrods are synthesized using the vapor phase transport method, and the magnetron sputtering is used to decorate the A1 nanoparticles （NPs） on a single ZnO microrod. The micro-PL and I-V responses are measured...ZnO microrods are synthesized using the vapor phase transport method, and the magnetron sputtering is used to decorate the A1 nanoparticles （NPs） on a single ZnO microrod. The micro-PL and I-V responses are measured before and after the decoration orAl NPs. The FDTD stimulation is also carried out to demonstrate the optical field distribution around the decoration of Al NPs on the surface of a ZnO microrod. Due to an implementation of AI NPs, the ZnO microrod exhibits an improved photoresponse behavior. In addition, AI NPs induced localized surface plasmons （LSPs） as well as improved optical field confinement can be ascribed to an enhancement of ultraviolet （UV） response. This research provides a method for improving the responsivity of photodetectors.展开更多
Cyclic voltammetry and chronopotentiometry have been used to study the Sb-doped Ti/SnO2 anodes prepared by magnetron sputtering. The results showed that magnetron sputtering condition influenced the surface morphology...Cyclic voltammetry and chronopotentiometry have been used to study the Sb-doped Ti/SnO2 anodes prepared by magnetron sputtering. The results showed that magnetron sputtering condition influenced the surface morphology and the properties of the anodes. After the Ti substrate was tempered in Ar at 600 ℃ for 1 h, Till1.5 on the surface generated from the acid etching was replaced by needle-like TiO2. The SnO2 coating on the above Ti substrate by magnetron sputtering with post-annealing was comprised of microrod and different with the traditional Ti/ SnO2 anode. The accelerated service life test showed that the microrod SnO2 anode gained the longest service time. The anode exhibited oscillations in the chronopotentiometry curves, and the microrod SnO2 coating almost dissolved after the life test. A model of layer-by-layer degradation mechanism for the anode was proposed.展开更多
Low-dimensional Bi2Fe4O9 nanosheets and microrods have been selectively prepared by a solvothermal method, from which the growth of the Bi2Fe4O9 crystals can be controlled by the variation of reaction conditions. Stru...Low-dimensional Bi2Fe4O9 nanosheets and microrods have been selectively prepared by a solvothermal method, from which the growth of the Bi2Fe4O9 crystals can be controlled by the variation of reaction conditions. Structure determination showed that the nanosheets are mainly exposed by {001} facets while the microrods are exposed by {110} facets. Ab- sorption spectra revealed that there are two bandgaps observed for both nanosheets （at 1.9 and 1.55 eV） and microrods （1.7 and 1.45 eV）, and they both would be available for the sunlight photocatalysis e ciently due to the intensive absorption ability in a wide region. Photocatalytic investigation demonstrated that the overall photocatalytic performance of the microrods is prior to that of the nanosheets due to the variation of bandgaps and exposed facets. The present report provides a useful alternative strategy for the controlling growth of nanostructures and/or microcrystals besides the present demonstration of the Bi2Fe4O9 crystals with diflerent bandgaps and facets that would be able to tune the corresponding photocatalytic ability selectively.展开更多
文摘Collective oscillations of free electrons generate plasmons on the surface of a material. A whispering-gallery microcavity effectively confines the light field on its surface based on the total reflection from its internal wall. When these two kinds of electromagnetic waves meet each other, the stimulated emissions from an individual ZnO microrod were enhanced more than 50-fold and the threshold was reduced after the whispering-gallery microcavity was coated with a monolayer of graphene and A1 nanoparticles. The improvement of the lasing performance was attributed to the synergistic energy coupling of the graphene/A1 surface plasmons with ZnO excitons. The lasing characteristics and the coupling mechanism were investigated systematically.
基金Acknowledgements The authors sincerely appreciate the help of Shufeng Wang and Yu Li at Peking University and Andong Xia at Institute of Chemistry Chinese Academy of Sciences for their technical support on time-resolved PL. This work was supported by the National Basic Research Program （No. 2013CB932903）, National Natural Science Foundation （Nos. 61275054, 61475035, and 11404289）, Jiangsu Province Science and Technology Support Program （No. BE2016177） and Natural Science Foundation of Zhejiang Province （No. LY17A040011）.
文摘It is essential to develop a single mode operation and improve the performance of lasing in order to ensure practical applicability of microlasers and nanolasers. In this paper, two hexagonal microteeth with varied nanoscaled air-gaps of a ZnO microcomb are used to construct coupled whispering-gallery cavities. This is done to achieve a stable single mode lasing based on Vernier effect without requiring any complicated or sophisticated manipulation to achieve positioning with nanoscale precision. Optical gain and the corresponding ultraviolet lasing performance were improved greatly through coupling with localized surface plasmons of Pt nanoparticles. The ZnO/Pt hybrid microcavities achieved a seven-fold enhancement of intensity of single mode lasing with higher side- mode suppression ratio and lower threshold. The mechanism that led to this enhancement has been described in detail.
基金supported by the National Natural Science Foundation of China(21567008,21263005)the Yangfan Project of Guangdong Province+2 种基金the Natural Science Foundation of Jiangxi Province(20133BAB21003,20161BAB203090)the Landing Project of Science and Technology of Colleges and Universities in Jiangxi Province(KJLD14046)the Graduate Innovation Project of Jiangxi Province(YC2015-S293)~~
文摘Ag2S/Ag2WO4 composite microrods,with lengths of 0.2-1μm and diameters of 20-30 nm,were fabricated by a facile sonochemical route.The as-synthesized products were intensively investigated by a series of physicochemical characterizations,such as N2 physical adsorption,X-ray diffraction,scanning electron microscopy,transmission electron microscopy,Fourier transform infrared spectroscopy,diffuser reflectance spectroscopy,X-ray photoelectron spectroscopy,photoluminescence spectroscopy and photocurrent response measurements.Ultrasonic irradiation yields an obvious improvement in the photocatalyst texture,for example,an increase in crystallinity and surface area.Moreover,sonochemically fabricated Ag2S/Ag2WO4 microrods display strong visible light absorption and a high transient photocurrent response.The produced intimate Ag2S/Ag2WO4interface between Ag2S and Ag2WO4 crystal phases largely promotes the separation of photogenerated holes and electrons.High photocatalytic activity and stability were obtained over Ag2S/Ag2WO4composite microrods.The dye degradation rate constant of Ag2S/Ag2WO4 was 4.7 times and 29.8times higher than that of bare Ag2WO4 and Ag2S,respectively.
基金supported by the National Natural Science Foundation of China (No. U1904215)the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions (TAPP)+1 种基金Natural Science Foundation of Jiangsu Province (No. BK20200044)Excellent doctoral dissertation of Yangzhou University and the Postgraduate Research & Practice Innovation Program of Jiangsu Province (No. KYCX19_2099)。
文摘Developing metal-organic framework(MOF)-based materials with good cyclic stability is the key to their practical application. Fluorinated organic compounds are usually highly chemically stability due to the high electronegativity of fluorine. Also, the pillared-layer structures based on coordination bonds have better structure and thermal stability than those based on hydrogen bonds. Herein, the fluorinated pillared-layer [Ni(2,3,4,5-tetrafluorobenzoic acid)(4,4-bipyridine)]nMOF([Ni(TFBA)(Bpy)]n) materials were constructed through a facile room-temperature solution reaction and used as electrode materials for supercapacitors. Surprisingly, the size/morphology of Ni(TFBA)(Bpy)nMOFs could be adjusted by varying the synthesis time. Benefting from the short ion diffusion length, unique pillar-layer structure, and strong intercomponent synergy of organic ligands, the Ni(TFBA)(Bpy)nMOF microrods showed a higher electrochemical energy storage capability than bulk MOFs. At the same time, compared to the non-fluorinated [Ni(benzoic acid)(Bpy)]nMOFs(31.5% capacitance decay), the fluorinated Ni(TFBA)(Bpy)n MOFs have a higher cycle stability with only 2.6% capacitance loss after 5000 cycles at 3 m A/cm^(2).
基金supported by National Natural Science Foundation of China(Grant No.51602184)Natural Science Foundation of Shaanxi Province(Grant no.2020JM-505)the Academic Talent Introduction Program of SUST(134080056)。
文摘The morphology of MAX phase powders significantly influences their microwave absorption properties.However,the traditional synthesis via solid-state reactions produces irregular powders,and the preparation of MAX phase powders with specific morphology remains a challenge.Herein,(VTiCr)Al C MAX phase microrods were fabricated for the first time in NaCl/KCl molten salts using vanadium,titanium,chromium,aluminum,and short carbon fibers as precursors.It was found that despite acting as a carbon source,carbon fibers also acted as sacrificial templates.By adjusting the molar ratio of metal powders and short carbon fibers,a series of carbon fiber@(V_(0.8)Ti_(0.1)Cr_(0.1))_(2)AlC microrods with core-sheath structure were also obtained.Carbon fiber@(V_(0.8)Ti_(0.1)Cr_(0.1))_(2)AlC microrods with a molar ratio of 8:2 showed the optimum microwave absorption performance.The reflection loss(RL)value reached up to–63.26 d B at 2.40 mm,and the effective absorption bandwidth(EAB)was about 5.28 GHz with a thickness of2.02 mm.Based on the electromagnetic parameter analysis and theoretical simulation,the enhanced microwave absorption performance was attributed to the synergistic effect of different factors like dielectric loss,magnetic loss,multiple reflection,and scattering.This work offers a facile route to modulate the morphology of MAX phase powders and may accelerate its application as microwave absorbers.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61475035 and 61275054the Science and Technology Support Program of Jiangsu Province under Grant No BE2016177the Collaborative Innovation Center of Suzhou Nano Science and Technology
文摘ZnO microrods are synthesized using the vapor phase transport method, and the magnetron sputtering is used to decorate the A1 nanoparticles （NPs） on a single ZnO microrod. The micro-PL and I-V responses are measured before and after the decoration orAl NPs. The FDTD stimulation is also carried out to demonstrate the optical field distribution around the decoration of Al NPs on the surface of a ZnO microrod. Due to an implementation of AI NPs, the ZnO microrod exhibits an improved photoresponse behavior. In addition, AI NPs induced localized surface plasmons （LSPs） as well as improved optical field confinement can be ascribed to an enhancement of ultraviolet （UV） response. This research provides a method for improving the responsivity of photodetectors.
文摘Cyclic voltammetry and chronopotentiometry have been used to study the Sb-doped Ti/SnO2 anodes prepared by magnetron sputtering. The results showed that magnetron sputtering condition influenced the surface morphology and the properties of the anodes. After the Ti substrate was tempered in Ar at 600 ℃ for 1 h, Till1.5 on the surface generated from the acid etching was replaced by needle-like TiO2. The SnO2 coating on the above Ti substrate by magnetron sputtering with post-annealing was comprised of microrod and different with the traditional Ti/ SnO2 anode. The accelerated service life test showed that the microrod SnO2 anode gained the longest service time. The anode exhibited oscillations in the chronopotentiometry curves, and the microrod SnO2 coating almost dissolved after the life test. A model of layer-by-layer degradation mechanism for the anode was proposed.
基金This work was supported by the National Natu-ral Science Foundation of China （No.21571166 and No.51271173） and the National Basic Research Pro- gram of China （No.2012CB922001）.
文摘Low-dimensional Bi2Fe4O9 nanosheets and microrods have been selectively prepared by a solvothermal method, from which the growth of the Bi2Fe4O9 crystals can be controlled by the variation of reaction conditions. Structure determination showed that the nanosheets are mainly exposed by {001} facets while the microrods are exposed by {110} facets. Ab- sorption spectra revealed that there are two bandgaps observed for both nanosheets （at 1.9 and 1.55 eV） and microrods （1.7 and 1.45 eV）, and they both would be available for the sunlight photocatalysis e ciently due to the intensive absorption ability in a wide region. Photocatalytic investigation demonstrated that the overall photocatalytic performance of the microrods is prior to that of the nanosheets due to the variation of bandgaps and exposed facets. The present report provides a useful alternative strategy for the controlling growth of nanostructures and/or microcrystals besides the present demonstration of the Bi2Fe4O9 crystals with diflerent bandgaps and facets that would be able to tune the corresponding photocatalytic ability selectively.
